The cuckoo comes on 21 April

In some parts of the country it was held that the cuckoo always made its first appearance on the twenty-first of April. Chambers adds that in the Middle Ages the bird was thought to know how long a person would live: asked respectfully on first hearing it in the morning, it would call once for every year left. Medieval preachers told of a lay brother who left his monastery on the strength of the cuckoo’s count and died two years later.